The present invention, in some embodiments thereof, relates to optics and, more particularly, but not exclusively, to an optically sensitive cell network, a method of producing an optically sensitive cell network, and a method and a system for stimulating an optically sensitive cell network.
The central nervous system (CNS) is the processing center for the nervous system. It receives information from and sends information to the peripheral nervous system. The two main organs of the CNS are the brain and spinal cord. The brain processes and interprets sensory information sent from the spinal cord. Both the brain and spinal cord are protected by three layers of connective tissue called the meninges.
Within the central nervous system is a system of hollow cavities called ventricles. The network of linked cavities in the brain (cerebral ventricles) is continuous with the central canal of the spinal cord. The ventricles are filled with cerebrospinal fluid which is produced by specialized epithelium located within the ventricles called the choroid plexus. Cerebrospinal fluid surrounds, cushions, and protects the brain and spinal cord from trauma. It also assists in the circulation of nutrients to the brain. Neurons are the basic unit of the nervous system. Neurons contain nerve processes which are “finger-like” projections that extend from the nerve cell body. The nerve processes consist of axons and dendrites which are able to conduct and transmit signals. Axons typically carry signals away from the cell body. They are long nerve processes that may branch out to convey signals to various areas. Dendrites typically carry signals toward the cell body. They are usually more numerous, shorter and more branched than axons. Axons and dendrites are bundled together into what are called nerves. These nerves send signals between the brain, spinal cord, and other body organs via nerve impulses. Neurons are classified as either motor, sensory, or interneurons. Motor neurons carry information from the central nervous system to organs, glands, and muscles. Sensory neurons send information to the central nervous system from internal organs or from external stimuli. Interneurons relay signals between motor and sensory neurons.
Various methods are known to stimulate neural tissue. A nerve cell can be stimulated in a number of different ways, including electrical, mechanical, thermal, chemical, and optical. A nerve is a filament of neural tissue composed of cells each having a cell body and one or more axons and dendrites.
A neuron will propagate an electrical impulse after applying a stimulus. The most common form of applying such stimulus is to form a transient current or voltage pulse applied through electrodes. It is recognized that optical energy can also be used to stimulate nerve fibers. One common way of providing light energy is by using a laser. Lasers are characterized by their wavelength and energy level. Classically, lasers have been used in biological applications for tissue ablation. Nevertheless, low power lasers are available for uses other than tissue ablation. The energy required for stimulation large populations of neurons is very small, and the energy required to stimulate an individual neuron is exceedingly small. The strength, duration and frequency of the optical energy can be adjusted to a range acceptable for stimulation of neural tissue.